Tensioning device for producing a linear pull



Sept. 27, 1949. H. DE HAVEN TENSIONING DEVICE FOR PBODUCING A LINEAR PULL :lilla Ille HUGH DE HAVE/v Filed June 20, 1946 Patented Sept. 2.7, 1949 PATENT @MIME 'EENSIONlN-.G )DEVICE FORBLQBUQINQ 7Glaims.

.1 The present ,invention relates 1"..0 tenolonlng means, v.and moie partieularly to a .device for converting `fluid pressure into a tensioning .force `of relatively great magnitude.

'The :present invention is particularly :adapted for mse'vvnereit is desiuedtohave a light-weight .seliieoritained .tensioning device for yproducing .a large -linear l.pulling `-force suddenly. ,.Asiillustraiiveof such dises, itne device ,of .thepresent 4inyention .has -ebeen =found ,Particularly eieotive .in lfzormection fwith emergency equipment for aimait such as-,crash belts-.and parachutes. As is well known, the deacceleratiorl Which takes place-when an :aironaitmakes .a .crash landing .is

freguently .fatal eeepecially to the pilot -linleSS Some means :is provided for .arresting .the ,pilotis fall at the moment of impact, ,As nonventional safety belts and :the like are -too .oenflnlilg .'fOr

praal-,ical -.usage, Marions devices .of y.the Spring Aactuated til-pe have `been.proposed for r.engagun;

.the rpilot when triggered .at fthe .momentof impaet )suon deviees., however, :have .been .-fouiid .to loe `1to0 slow in :action and also zyeigy cumbersome and dinicult lio set ivvhioli has :rendered Athere vggenera-15.15' lineart' v.factory- By ,installing fa .device .of the present invention .as :the tensioningnieans theymeouisiterinstantaneolis action and ;-s.tr.o11g-.iorce may-:be lobtained tand .at the .same time the-;.device;is adeeirably .compact .and Aof' light weight. With respect to parachutes, the dexioe of :the present rinvention, 4when installed :fbetveeen the ,parachute and :the load, is particularly .effective for .arresting -.the descent :of the :loadat .fthe -instafirt :before eontaot with :the .ground ythereby cushioning the shockof'landing. '."Here 1*0 again, .the feompaetness :and Viight :Weight :of -the device sand its fability ato provide the -relatively great I.tensioning fforce required instantaneously makes it-ne ,device invaluable fior this `pur-pose.

In view-.of :the advantages of 'the @device of the present invention in1=that-`it-mayfbe made of extremely light construction,-if-desired, andeat the same time may -be utilized fto obtain 'linear tensioning for-ees of relatively vnlhigh magnitude be readily controlled so that the tensioning ac- :ltion-is relatively I slow or -fast, and ithe actuation of the 'device may rbe -delayed -or accomplished substantially instaneouslyif desired.

v"The d'foregoing Kand other advantages Aoi the invention will be readily -apparent '-from ythe following description of -a specific ,embodiment of the invention ahonnin tine accompanying N@livelliiine, which Figure l .is ,side .View of .theaasemloleiede- .viool '.Fie. 2 ,is .a .inagmontary .oroee .seotional .new .of .oneend .of `the nietige; and

v3 .is a .fragmentary oioaseotional view of end ...of 'the device .opposite to .thotaliown dei/ice .of .the .nreeentinvention is baeed .on .the .conception gtliat ailatiioe .woven time .oom-

oitrands wliloliaieginterwoven.orloiaded .on tno diagonal 'to :formooinloineilleitzkland .and

.rianteliancl lhelices .may .be .anortened llene-thwiee by increasing 'the 'diameter =.of ille tube, .i leg, by

.expanding the tnlie Nradially.. .effeotf the ivoren time of .grossed 'helix ...stianlds .rotations like .Qomlim 'tion of toggle Jjoints to '.tianalate o eitudinal A.motion :AS .e Kieaiilt el tioiteninginltlieilenetlo.of .the .tube theme iainrovided .a .tensioning forge .which is A.op.emita/.e

tno ends .of .the tube Referring 'to the drawing, ltlieeiziiter or 'ten- .sioninetune .l is ooinpoaed .ofetitands .woven on 'ine diagonal sas I.described -above fio `onfn .a plutheliape of. a continuelle tube ine oftl1e-strands onlin diagonal in .the ,form of a ,nluitality.oflielices.,lt1ie desliloid toggle .eieot .is .created onion .causes 'the tube Lto ,shorten `its .diameter :is inoreas d. n apeoiiio :example .of .auch .woven fulmine .or .Jannes .usen .satiefaotoi'ily :the .nylon .braidiio Zw-134.38 ,manufactured "ny 'the ilone 'webbing Campani. of if desired, the anterior .tensioninetiine be formed doublelgyltlie addition .of aseoorfd .similar tensioning tube ..2 ...By .the use of a multiple Aoonsllrnc-tion,the daoacity ,ofltlie device .may flee mateiieilv inere .d as .fciesired .It "is desired 'to .make It. :outer .tube l .and .also any .additional fteneionine I.tubes.suoli Y:as the .strengtli to translate .radially .f n.

.suites .'.irito :tensioning forces of leigh .in .,nltlile. :It is alec .desirable to Seleota material `ilzlzlicsli is .ooinnaretively free imm .toraional .Leaistanoe .to .nexmitireee ninotioninaofthe toggle .eleot no@ sneoiioexaninle, .ainaterlal .whiohnasbeen gleed 5o satisiaetorily inoarlgyinaoutihe,invention .is-ille welllknown synthetic -ber .having fthe .trade name".nylon. ,Snolmilonnhers orstrandsaate .readilyaadaptableto Meeting orrnraidingltoiiorm the .outer-iones .I .anilas .desorihed ahime and attne `sangue time .are euiioiently `stione ;..t.o

3 used in devices designed to exert tensioning forces of high magnitude and are relatively free from torsional resistance. Other suitable materials may be utilized if desired.

In order to exert a radially expanding force along the inner surfaces of the outer tubes I and 2, it is preferred to utilize an inner tube 3 which is expansible and which is substantially fluid-tight. The inner tube is adapted to operate in the nature of a bladder for exerting a radial force, when expanded, along substantially the entire inner surface of the outer tubes I and 2. The inner tube may be of rubber or the like.

The fluid pressure to be applied within the inner tube 3 is preferably applied from a source contained within the device itself. In order to provide a self-contained unit, a convenient source of fluid pressure which may be disposed within the inner tube 3 is an ignitible gas-evolving pressure-producing material, such as ordinary black gunpowder or similar material. The gunpowder may be wrapped in paper or a tape, i. e., spread out or pocketed, in any desired fashion so as to provide fast or slow burning. In the drawing, a wrapped gunpowder charge is indicated by the reference numeral d. As is well known in the art, the characteristics of the burning also may be readily varied by varying or changing the composition of the ignitible charge. The preparation and modification of gunpower and like charges to provide varying characteristics as to the rate of burning and the amount of pressure created is v well known to one skilled in the art, and the use wrapped powder charge 4.

In order to protect the tube 3 from the flame produced when gunpowder is ignited, the gunpowder charge 4 and the electric squib 5 may be enclosed in a sheath 8 of material which is resistant to iame and thus will act as a flame shield. Satisfactory results have been obtained, for ex'- ample, by the use of a tube constructed of cotton braid which has been dipped in ammonium stearate. The ends of the flame shield or tube may be tied in any convenient fashion while, at the same time, permitting the lead wires 9 of the electric squib 5 to extend therefrom.

In assembling the completed device of the present invention, the ends of the device may be sealed by means of plugs I and II which, in a preferred embodiment, are in the shape of a dumbbell. For convenience, the plug I0 has an axial bore I2 adapted to receive the lead wires 9 from the electric squib 5. The inner tube 3 and the outer tubes I and 2 are pulled over the plug lil and are securely wrapped in this position by means of a wrapper I3. The wrapper I3 may comprise, for example, a length of cotton braid which is approximately three-fourths inches wide and ofthe order of twenty inches long. This braid is circumferentially wound about the outer tubes I and 2, inner tube 3, and the lower narrow portion of the plug Ill to form an annular bead therearound. The outer tubes I and 2 are then pulled backwardly over the bead formed by the wrapper i3 and are again boundto the plug It by means of a second wrapper I4 which, as a spe- 4 cie example, may consist of iiberglas tape of the order of one-half inch in width and approximately two feet long.

After the winding of the second wrapper Ill has been completed, the outer coverings I and 2 are drawn over both beads formed by the wrappers I3 and I4 and around the outer end of the plug I D where they are securely tied as close to the plug Ill as possible, preferably in the form of a bowline knot I5.

As mentioned above, the lead wires 9 from the electric squib 5 are received through the axial bore I2 of the plug I0. In order to seal the device against loss of compression through the bore i2, it is preferred to provide the plug Il) with a threaded end plug I6 and to utilize a packing Il composed of a suitable sealing material, such as adhesive tape. The lead wires 9 may be brought out through the external tubes of the device by inserting a sharp instrument between the strands oi the outer tubes I and 2 to form an opening through which the lead wires may be drawn.

The Opposite end of the device is formed in substantially the same way utilizing wrappers I8 and it, and the ends oi the outer tubes I and 2 are similarly tied in theform of a bowline knot 2li. The knots I5 and 2li provide a convenient attachnient means at each end of the tube by which connection can be made directly with the outer tubes i and 2. It is not necessary, in the embodiment shown in the drawing, to provide the dumbbellshaped plug i l with any openings such as in the case of the Aplug i6. Other means for closing the ends of the tubes may be utilized if desired, but the foregoing is given as illustrative of a practical way which will not malfunction during normal usage of the device.v

lit will be apparent to one skilled in the art in light oi the above description that the dimensions 'of the device may be varied over a wide range depending upon the operating characteristics of the device which are desired and the strengths of the materials employed. For most uses, the length of the tube need not exceed about three to six feet, although the maximum size of the tube is limited merely by the strength of the materials employed. A tube having a pulled-down diameter, for example, of the order of one-half inch has been utilized satisfactorily in devices of such Y lengths.

Knowing the dimensions of the assembly and the angle between the diagonal elements, the amount of pull to be derived for any internal pressure may be readily calculated and may be checked experimentally for any given device if desired. In the specific examples given above, a charge of as little as about one to three grams of gunpowder per linear foot will be sufcient to provide a tensioning force of high magnitude.

With a device constructed as described above, it is possible to obtain a decrease in length of about thirty percent and to obtain an initial tensioning pull of about 1500 pounds with a gas pressure of the order of 400 pounds per square inch. Despite the very great tensioning force provided by the device, however, it may be of very light weight such as, for example, nine ounces for a three foot unit.

When a gunpowder charge is utilized, the device may be actuated in a matter of two to three thousandths of a second by the electric squib, which, in View of the light weight of the device,

vhas made the device particularly adaptable for use with parachutes and landing equipment as described above.

In vieW ofthe above description of a specific embodiment of the invention, it will be apparent that the device Will be susceptible to variation by one skilled in the art, and all such Variations are intended to be included within the scope of the invention. y

I claim as my invention:

1. A tensioning device for producing a linear pull comprising an outer tube of strands woven on the diagonal to form a plurality of helices, an expansible substantially gas-proof inner tube confined within said outer tube, a source of gaseous pressure within said inner tube comprising a charge of ignitible gas producing material,

means for igniting said material, and attachingr means on the ends of the outer tube.

2. A tensioning device for producing a linear pull comprising an outer tube of strands Woven on the diagonal to form a plurality of helices, an expansible substantially gas-proof inner tube conned Within said outer tube, a source of gaseous pressure Within said inner tube comprising a charge of gunpowder, means for igniting said charge, and attaching means on the ends of the outer tube.

3. A tensioning device for producing a linear pull comprising an outer tube of strands Woven on the diagonal to form a plurality of helices, an expansible substantially gas-proof inner tube confined within said outer tube, a source of gaseous pressure Within said inner tube comprising a charge of ignitible gas-producing material, a name resistant covering substantially enclosing said charge, means for igniting the charge, and attaching means on the ends of the outer tube.

4. A tensioning device for producing a linear pull comprising an outer tube composed of strands Woven on the diagonal to form a plurality of helices, an inner tube of eXpansible substantially fluid-proof material, a pair of plugs closing the ends of said tubes and securely attached thereto, connecting means secured to each end of the outer tube, a source of gaseous pressure, means extending through one of said plugs for eiectuating the release of gas from said source within the inner tube, and attaching means on the ends of the outer tube.

5. A tensioning device for producing a linear pull comprising an outer tube composed of strands woven on the diagonal to form a plurality of helices, an inner tube of expansible substantially fiuid-proof material, a pair of plugs of dumbbell shape extending into the ends of said tubes, said tubes being Wrapped around and bound to the narrow sections of the duinbbell plugs by means of binding tapes circumferentially wound therearound, a source of gaseous pressure within said inner tube comprising a charge of ignitible gas-producing material, means extending through one of said plugs for igniting said charge, and attaching means on the ends of the outer tube.

6. A tensioning device for producing a linear pull comprising an outer tube formed of strands Woven on the diagonal to provide a plurality of helices, an expansible, substantially gas-proof inner tube inside said outer tube, means for creating a substantially instantaneous gaseous pressure within said inner tube to effect a sudden 1inear contraction of the device, and attaching means on the ends of the outer tube.

7. A tensioning device comprising an outer tube formed of strands woven on the diagonal in the form of a plurality of helices, an inner tube adapted to be iniated by gaseous pressure and disposed Within said outer tube for radially expanding the outer tube thereby shortening its length, and means for creating a substantially instantaneous gaseous pressure Within said inner tube, said outer tube being extended beyond the ends of the inner tube to form attaching means at each end of the tube.

HUGH DE HAVEN.

REFERENCES CITED The following references are of record in the lle of this patent:

UNITED STATES PATENTS Number Name Date 814,472 Noonan Mar. 6, 1906 2,211,478 Pierce Aug. 13, 1940 

